Create me an autoresponder / fake chat for my website.

I need a small application on my site that shows messages as if it's an user (so a fake chatbox for example) It should show a few lines / fake messages, ask for user input. Have the use input the answer and have it show up in the "chat box" And again, "post" a few lines/messages after that. It shouldn't be too complicated and I need to done fast.